Rename ParseIdentifierOrStrictReservedWord to simply ParseIdentifier and
replace the old ParseIdentifier with ParseNonRestrictedIdentifier for the
disallow_restricted_identifier case. It reuses the new ParseIdentifier.

Clients that relied on the is_strict_reserved output parameter can simply check
the token themselves.

Change-Id: I49b096d7ffbfff391483e9c18c9504e5d353e97b
Reviewed-on: https://chromium-review.googlesource.com/c/1357057Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57994}